<?php

// +----------------------------------------------------------------------

// | ThinkPHP [ WE CAN DO IT JUST THINK IT ]

// +----------------------------------------------------------------------

// | Copyright (c) 2006-2012 http://thinkphp.cn All rights reserved.

// +----------------------------------------------------------------------

// | Licensed ( http://www.apache.org/licenses/LICENSE-2.0 )

// +----------------------------------------------------------------------

// | Author: 麦当苗儿 <zuojiazi@vip.qq.com> <http://www.zjzit.cn>

// +----------------------------------------------------------------------



namespace OT;

use Think\Db;



//数据导出模型

class Database{

    /**

     * 文件指针

     * @var resource

     */

    private $fp;



    /**

     * 备份文件信息 part - 卷号，name - 文件名

     * @var array

     */

    private $file;



    /**

     * 当前打开文件大小

     * @var integer

     */

    private $size = 0;



    /**

     * 备份配置

     * @var integer

     */

    private $config;



    /**

     * 数据库备份构造方法

     * @param array  $file   备份或还原的文件信息

     * @param array  $config 备份配置信息

     * @param string $type   执行类型，export - 备份数据， import - 还原数据

     */

    public function __construct($file, $config, $type = 'export'){

        $this->file   = $file;

        $this->config = $config;

    }



    /**

     * 打开一个卷，用于写入数据

     * @param  integer $size 写入数据的大小

     */

    private function open($size){

        if($this->fp){

            $this->size += $size;

            if($this->size > $this->config['part']){

                $this->config['compress'] ? @gzclose($this->fp) : @fclose($this->fp);

                $this->fp = null;

                $this->file['part']++;

                session('backup_file', $this->file);

                $this->create();

            }

        } else {

            $backuppath = $this->config['path'];

            $filename   = "{$backuppath}{$this->file['name']}-{$this->file['part']}.sql";

            if($this->config['compress']){

                $filename = "{$filename}.gz";

                $this->fp = @gzopen($filename, "a{$this->config['level']}");

            } else {

                $this->fp = @fopen($filename, 'a');

            }

            $this->size = filesize($filename) + $size;

        }

    }



    /**

     * 写入初始数据

     * @return boolean true - 写入成功，false - 写入失败

     */

    public function create(){

        $sql  = "-- -----------------------------\n";

        $sql .= "-- Think MySQL Data Transfer \n";

        $sql .= "-- \n";

        $sql .= "-- Host     : " . C('DB_HOST') . "\n";

        $sql .= "-- Port     : " . C('DB_PORT') . "\n";

        $sql .= "-- Database : " . C('DB_NAME') . "\n";

        $sql .= "-- \n";

        $sql .= "-- Part : #{$this->file['part']}\n";

        $sql .= "-- Date : " . date("Y-m-d H:i:s") . "\n";

        $sql .= "-- -----------------------------\n\n";

        $sql .= "SET FOREIGN_KEY_CHECKS = 0;\n\n";

        return $this->write($sql);

    }



    /**

     * 写入SQL语句

     * @param  string $sql 要写入的SQL语句

     * @return boolean     true - 写入成功，false - 写入失败！

     */

    private function write($sql){

        $size = strlen($sql);

        

        //由于压缩原因，无法计算出压缩后的长度，这里假设压缩率为50%，

        //一般情况压缩率都会高于50%；

        $size = $this->config['compress'] ? $size / 2 : $size;

        

        $this->open($size); 

        return $this->config['compress'] ? @gzwrite($this->fp, $sql) : @fwrite($this->fp, $sql);

    }



    /**

     * 备份表结构

     * @param  string  $table 表名

     * @param  integer $start 起始行数

     * @return boolean        false - 备份失败

     */

    public function backup($table, $start){

        //创建DB对象

        $db = Db::getInstance();



        //备份表结构

        if(0 == $start){

            $result = $db->query("SHOW CREATE TABLE `{$table}`");

            $sql  = "\n";

            $sql .= "-- -----------------------------\n";

            $sql .= "-- Table structure for `{$table}`\n";

            $sql .= "-- -----------------------------\n";

            $sql .= "DROP TABLE IF EXISTS `{$table}`;\n";

            $sql .= trim($result[0]['Create Table']) . ";\n\n";

            if(false === $this->write($sql)){

                return false;

            }

        }



        //数据总数

        $result = $db->query("SELECT COUNT(*) AS count FROM `{$table}`");

        $count  = $result['0']['count'];

            

        //备份表数据

        if($count){

            //写入数据注释

            if(0 == $start){

                $sql  = "-- -----------------------------\n";

                $sql .= "-- Records of `{$table}`\n";

                $sql .= "-- -----------------------------\n";

                $this->write($sql);

            }



            //备份数据记录

            $result = $db->query("SELECT * FROM `{$table}` LIMIT {$start}, 1000");

            foreach ($result as $row) {

                $row = array_map('mysql_real_escape_string', $row);

                $sql = "INSERT INTO `{$table}` VALUES ('" . implode("', '", $row) . "');\n";

                if(false === $this->write($sql)){

                    return false;

                }

            }



            //还有更多数据

            if($count > $start + 1000){

                return array($start + 1000, $count);

            }

        }



        //备份下一表

        return 0;

    }



    public function import($start){

        //还原数据

        $db = Db::getInstance();



        if($this->config['compress']){

            $gz   = gzopen($this->file[1], 'r');

            $size = 0;

        } else {

            $size = filesize($this->file[1]);

            $gz   = fopen($this->file[1], 'r');

        }

        

        $sql  = '';

        if($start){

            $this->config['compress'] ? gzseek($gz, $start) : fseek($gz, $start);

        }

        

        for($i = 0; $i < 1000; $i++){

            $sql .= $this->config['compress'] ? gzgets($gz) : fgets($gz); 

            if(preg_match('/.*;$/', trim($sql))){

                if(false !== $db->query($sql)){

                    $start += strlen($sql);

                } else {

                    return false;

                }

                $sql = '';

            } elseif ($this->config['compress'] ? gzeof($gz) : feof($gz)) {

                return 0;

            }

        }



        return array($start, $size);

    }



    /**

     * 析构方法，用于关闭文件资源

     */

    public function __destruct(){

        $this->config['compress'] ? @gzclose($this->fp) : @fclose($this->fp);

    }

}